AVPlayer plays video composition result incorrectly

Question

I need a simple thing: play a video while rotating and applying CIFilter on it.

First, I create the player item:

AVPlay         


        

Answer 1

UPDATE: There comes out to be an easier way to "change" the AVPlayerItem video dimensions during playback - set the renderSize property of video composition (can be done using AVMutableVideoComposition class).

MY OLD ANSWER BELOW:

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After a lot of debugging I understood the problem and found a solution. My initial guess that AVPlayer still considers the video being of the original size was correct. In the image below it is explained what was happening:

As for the solution, I couldn't find a way to change the video size inside AVAsset or AVPlayerItem. So I just manipulated the video to fit the size and scale that AVPlayer was expecting, and then when playing in a player with correct aspect ratio and flag to scale and fill the player area - everything looks good. Here is the graphical explanation:

And here goes the additional code that needs to be inserted in the applyingCIFiltersWithHandler block mentioned in the question:

... after Step 3 in the question codes above

// make the frame the same aspect ratio as the original input frame
// by adding empty spaces at the top and the bottom of the extent rectangle
CGFloat newHeight = originalExtent.size.height * originalExtent.size.height / extent.size.height;
CGFloat inset = (extent.size.height - newHeight) / 2;
extent = CGRectInset(extent, 0, inset);
sourceImage = [sourceImage imageByCroppingToRect:extent];

// scale down to the original frame size
CGFloat scale = originalExtent.size.height / newHeight;
CGAffineTransform scaleTransform = CGAffineTransformMakeScale(scale, scale);
[transformFilter setValue:sourceImage forKey: kCIInputImageKey];
[transformFilter setValue: [NSValue valueWithCGAffineTransform: scaleTransform] forKey: kCIInputTransformKey];
sourceImage = transformFilter.outputImage;

// translate the frame to make it's origin start at (0, 0)
CGAffineTransform translation = CGAffineTransformMakeTranslation(0, -inset * scale);
[transformFilter setValue:sourceImage forKey: kCIInputImageKey];
[transformFilter setValue: [NSValue valueWithCGAffineTransform: translation] forKey: kCIInputTransformKey];
sourceImage = transformFilter.outputImage;